feat(cabinet): migrate all icons to the panel's Phosphor set

Replace the cabinet's hand-written heroicons-style SVG icon components with
the Remnawave panel's own icon family — Phosphor via react-icons/pi (Duotone).
All icons now live in a single central barrel (src/components/icons:
index + extended-icons + editor-icons, 144 icons); every feature file imports
from it instead of redefining inline SVGs (~440 icon defs removed).

- Add react-icons dependency
- Desktop nav (AppShell) now uses the central Phosphor icons, removing a
  stroke-vs-duotone inconsistency the partial migration introduced
- Icons with custom props (SortIcon's direction, expandable chevrons) kept as
  thin Phosphor wrappers; the RemnawaveIcon brand logo and animated SVGs
  (checkmarks, spinners) are intentionally left as-is
- Restore the original per-call-site icon sizes wherever the centralized
  default differed (211 call sites)

src/components/icons/editor-icons.tsx

@@ -0,0 +1,85 @@
+import {
+  PiTextBDuotone,
+  PiTextItalicDuotone,
+  PiTextUnderlineDuotone,
+  PiTextStrikethroughDuotone,
+  PiTextHOneDuotone,
+  PiTextHTwoDuotone,
+  PiTextHThreeDuotone,
+  PiListBulletsDuotone,
+  PiListNumbersDuotone,
+  PiQuotesDuotone,
+  PiCodeBlockDuotone,
+  PiTextAlignLeftDuotone,
+  PiTextAlignCenterDuotone,
+  PiHighlighterDuotone,
+} from 'react-icons/pi';
+
+import { cn } from '@/lib/utils';
+
+interface IconProps {
+  className?: string;
+}
+
+/**
+ * Rich-text editor toolbar icons — Phosphor (react-icons/pi) Duotone, the
+ * panel's icon family. Shared by the TipTap toolbars in AdminNewsCreate and
+ * AdminInfoPageEditor. Names match the historical local definitions so the
+ * toolbars import instead of hand-rolling SVGs.
+ */
+
+export const BoldIcon = ({ className }: IconProps) => (
+  <PiTextBDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const ItalicIcon = ({ className }: IconProps) => (
+  <PiTextItalicDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const UnderlineIcon = ({ className }: IconProps) => (
+  <PiTextUnderlineDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const StrikeIcon = ({ className }: IconProps) => (
+  <PiTextStrikethroughDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const H1Icon = ({ className }: IconProps) => (
+  <PiTextHOneDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const H2Icon = ({ className }: IconProps) => (
+  <PiTextHTwoDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const H3Icon = ({ className }: IconProps) => (
+  <PiTextHThreeDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const ListBulletIcon = ({ className }: IconProps) => (
+  <PiListBulletsDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const ListOrderedIcon = ({ className }: IconProps) => (
+  <PiListNumbersDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const QuoteIcon = ({ className }: IconProps) => (
+  <PiQuotesDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const CodeBlockIcon = ({ className }: IconProps) => (
+  <PiCodeBlockDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const AlignLeftIcon = ({ className }: IconProps) => (
+  <PiTextAlignLeftDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const AlignCenterIcon = ({ className }: IconProps) => (
+  <PiTextAlignCenterDuotone className={cn('h-5 w-5', className)} />
+);
+
+export const HighlightIcon = ({ className }: IconProps) => (
+  <PiHighlighterDuotone className={cn('h-5 w-5', className)} />
+);